Hello, I am a horticulture major, but I also study landscape planning and design. You need to make renderings and elevations, and you need to have a good grasp of the shape and structure of the object to show a sense of space and volume.

In short, sketching is the foundation, and you should learn it. Of course, learning painting is imminent, and you need to experience and feel constantly in the process of continuous learning. If you decide that design is your future goal, then I would suggest that you keep practicing sketching. At the same time, it is necessary to learn colored gouache.

You said that light and shadow are not good, that's right. Sketch deals with the relationship between light and shadow. If you take design as your future goal, you have to take a long-term view, don't rush for success, and lay a good foundation step by step.

In addition, when you feel that your painting is bad and you feel uncomfortable after painting for a period of time, it may be a precursor to your improvement in painting skills. Just stick to it.

I hope my suggestion is helpful to you.